Apparatus for mixing the contents of storage and containment devices such as IBCs (Intermediate Bulk Containers) in-situ in the container is known. It provides the advantage that the constituents of mixtures such as foodstuffs and pharmaceuticals can be mixed in-situ in the container in which they are being stored and/or transported without the need to transfer them to a separate mixer and back again, thus saving time and expense. It also removes the need for cleaning of the mixing device before processing of the next mixture can occur, also saving time. Generally, such devices operate by moving the container including the contents relative to a fixed support, supported for example on the ground, so that the contents moves inside the container and mixing occurs. An effective form of movement can be rotation of a container such as an IBC, end over end. In the art, such processes are commonly called tumble blending.
Known tumble blending apparatus can suffer from some disadvantages in some specific uses. For example, complete mixing of some constituent types is sometimes difficult to achieve for the very reason that the apparatus is only capable of mixing by movement of the entire container, and this can be a limitation on the utility of such devices when the constituents include particulates and fats. Also, with tumble blending there can be a tendency for the tumbling action to create balls of fat-rich powder which do not become homogeneously mixed. Incomplete mixing can also occur if insufficient airspace (known as ullage) is left in the container because the space available for movement of the contents is limited.
Recently it has been suggested that problems such as these could be overcome if more conventional mixing procedures, such as for example high, shear mixing, could be used in combination with tumble blending. However, a problem lies in how to incorporate such procedures into a tumble blender type device without sacrificing its many advantages or compromising its operation.
Furthermore, it is often required to add constituents whilst mixing is proceeding, which clearly presents some unique challenges if the container to which the constituents must be added is large and heavy and rotating at speed.
The present invention seeks to address problems such as these.